Shingles are typically small, thin sheets of building material that are used in overlapping rows to protect the interior of a house from inclement weather. Historically, shingles have been constructed from a number of compositions, including natural slate, metal, fibrous cement, ceramics, wood, concrete and bitumen compounds.
In recent years, synthetic shingles have gained favor in the steep-slope roofing industry. Synthetic shingles are advantageous over conventional shingles because they do not absorb water, can be manufactured in virtually any shape, size and style, are strong and lightweight, and provide a total installed roofing cost that is substantially less costly than that of slate shingles. Furthermore, synthetic shingles can be made with increased fire retardancy and increased impact resistance, both of which are significant advantages over wood shakes and wood shingles.
Typically, synthetic shingles are made from combinations of resin, fillers and color concentrates. Although a number of different polymers have been used, synthetic shingles are most commonly constructed from polyolefin resins. Commonly selected resins may range from polyethylene to polypropylene-type structures.
Although initially effective, insufficient durability and longevity of prior art synthetic shingles have limited their popularity in the marketplace. The limited lifespan of existing synthetic shingles largely results from extended exposure to the sun's intense ultraviolet (UV) radiation, which degrades the molecular structure of typical synthetic shingles, causing the shingle to embrittle, fade or deform.
In an attempt to combat UV degradation, synthetic shingle manufacturers have added UV-resistant fillers (also referred to as “additives”) to the underlying plastic resin mixture. Other manufacturers have built color concentrates into their resins that include UV inhibitors, antioxidants and other chemicals that discourage the pigment from changing hue over time. These additives and color concentrates are new in the marketplace, and their long-term effectiveness is unproven.
Despite the limited advances in the industry, there continues to exist a need for an improved synthetic shingle that overcomes the inherent vulnerabilities of prior art synthetic shingles.